Metalworking



5 Sheets-Sheet l METALWORKING A. LIEBERGELD Filed Jan. 14, 1937 QN ww April 11, 1939.

April 1939- A. LIEBERGELD 2,153,839

METALWORKING Filed Jan. 14, 1937 5 Sheets-Sheet 2 April 1939- A. LIEBERGELD 2,153,839

' METALWORKING Filed Jan. 14, 1957 5 Sheets-Sheet 3 Apri 11, 1939- A. LIEBERGELD METALWORK ING Filed Jan. 14, 1937 5 Sheets-Sheet 4 April 1939- A. LIEBERGELD 2,153,839

METALWORK ING Filed Jan. 14, 1937 5 Sheets-Sheet 5 DEAD CENTER DEAD cEN'TER QZfreczi LtebrlgeZd,

Patented Ap 11, 1939 UNITED STATE 2,153,839 METALWORKING Alfred Liebergeld, Nurembe g, Germany, assignor to Fritz Singer, Nuremberg, Germany Application January 14, 1937, Serial No. 120,509

InGermany February 11, 1936 9 Claims.

This invention relates to a rolling-drawing method for reducing at intermittent sections the cross-section made of met of solid and hollow pieces of work a1 and consists in the feature that upon short sections following one another of the cold piece of work (or heated tohot deformation thickness of ments operat tubes by means of oscillating seged from a fixed fulcrum.

It is an object of this invention to provide a new and improved type of rolling-drawing machine. A further object is to provide a new and improved method for reducing the cross-sectional area of metal stock. A still further object is to provide a rolling-drawing method of reducing the cross-section of metal tubes'bars and rods in which substantially less powerful forces of deformation are required for obtaining the same degree of deformation obtainable by known methods.

Another object is to. provide a method of reducing the cross-section of metal tubes in which the shaping of the tube and smoothing the surface thereof the reducing to provide a are effected in the same stroke of element. An additional object is method of operation in which the reducing elements or segments are lifted off of the work piece'for a relatively long period. permitting more time for rotating and feeding the work piece and thereby avoiding shocks. A further object is to-provid e a means of reducing the wall thickness of metal tubes without distortion of the tube surface. Another object is to provide a new and improved means for protecting the reducing elements against overloading. Other objects will appear hereinafter.

In accordance with the invention, the reducing elements comprise segments which oscillate or swing from fulcra while said fulcra move in a direction parallel to the axis of the metal stock being worked. By simultaneous movement of the segments and fulcra, deforming forces are produced which act diagonally upon the piece of work and also parallel to the axis of the piece of work. For the forces actin purpose of producing the deforming diagonally upon the piece of work,

the fulcra of symmetrically arranged segment pieces are m line parallel piece of work, with which is combined a clear rolling down of' opposite confining surfaces of these segment pieces. For producing the deforming forces acting parallel to the axis of the piece of work, according to the invention, not 5 only the fulcra but also allpoints of the rolling down surfaces of the segment pieces are displaced by greater or smaller amounts in the direction of the axis of the piece of work.

As contrasted with the deformation produced by a mere rolling movement of the segment pieces, the rolling-drawing method according to the invention shows the advantage that substantially less powerful forces of deformation are required for obtaining the same degree of deformation, because owing to the component of the forces of deformation acting parallel to the axis of the piece of work the displacement of material is made substantially easier.

According to the invention, the straight-line reciprocating movement of the fulcra of 'the symmetrically arranged segment pieces parallel to the axis of the work piece is efiected by suitable lever or fulcra steering guides driven by known drive means such as, for instance, a crank.

In the case of rolling mills heretofore known in which the rolling segments are mounted in very powerfully built slides and the rolling down of the roller segments is produced by a reciprocating movement of the slide, there is the drawback that very large masses must be reciprocated inrapid sequence. This has the disadvantage, apart from the extremely difficult construction of such machines, that the number of strokes must be held comparatively low and furthermore that a rapid 86 wear of the machine parts necessitating frequent interruptions of operation and repairs must necessarily occur. The use of lever or steering guide means has the advantage that it permits the greatest possible reduction of the weight of the 4 masses to be reciprocated.

In order to accomplish the exact rolling down action of the limiting surfaces 'of the segment pieces one may resort to means known per se, for instance, gear segments provided on the segment pieces, the teeth of which mesh witheach' other and one of which is in engagement with a rack (toothed rod), However, to impartto the working parts of the segment pieces during the rolling down action of the latter a movement in so the direction of the stretching of the piece of work, the rack must not, as in the caseof the known roiling mills, be connected solidly with the machine frame but must be movedback and forth in a suitable manner in the direction'of the.

axis of the piece of work; this back and forth (reciprocating) movement may be controlled by a crank or cam drive.

According to the invention, the rolling down action of the segment pieces, as well as the parallel displacement of the working parts of the same, is effected by segment steering means which have one of their ends jointedly connected to the segment pieces, preferably near the working ends of said segments, and their other ends to sliding members adjustably secured in the machine frame.

As the simultaneous parallel displacement of the rolling down-surfaces of the segment pieces herein provided must necessarily take place also on the return stroke, this wduld have as its consequence that the segment pieces, after rotation of'the tube on the return stroke would impact on the swelling involved by the oval shape of the tube section stretched during the forward stroke and produce, with their deforming forces acting parallel to the axis of the piece of work, deformations of shape or distortion which would spoil the stretched tube. According to the invention, therefore, means are provided which lift the rolling segments off the tube on the return stroke so that they may freely slide over the part of the work piece stretched during the return stroke. This arrangement has the further advantage that for the rotation and the feed of the tube the entire period which is required for carrying, out the return stroke is available. In addition, according to the invention, means are provided to protect the segment pieces, the lever and connecting rod guidemeans from overloading.

A rolling-drawing machine for the stretching of tubes according to the invention is illustrated in the accompanying drawings, in which:

Figure 1 is a plan view of the machine, partly in section, showing the position of the segment pieces during the return stroke;

Figure 2 is a side elevational view of the machine in the same position of the parts thereof as shown in Figure 1, partly in section;

Figure 3 is a similar view of the machine as Figure .1, showing the position of the -segment pieces prior to the start of the rolling-drawing operation;

Figure 4 is a similar view as Figures 1 and 3, and shows the position of the segment pieces in the forward dead center position of the driving cranks.

In Figures 3 and 4 the mandrel lathe is omitted.

In Figure 5 the crank circle is illustrated and it is shown how the various operating steps are distributed over the segments of the crank circle.

Mounted in the machine frame I are the verticallyarranged crank shafts 2, 2' which carry the crank pins 3, 3. One of the two crank shafts is driven by a transmission or direct by an upright motor. The drive of the other crank shaft is effected by an intermediate shaft 4, the bevelledgears 5, 5 of which are in engagement with similar bevelled gears rigidly mounted on .the crank shafts 2, 2 but not shown in the drawings. The arrows indicate the movement of the two crank shafts in opposite directions.

The connecting rods 6, 6' are rotatably connected by means of the pins 1, I with continuations of the fulcra guide pieces 8, 8 of the fulcra steering guide means. The fulcra steering guide means consist of the fulcra guide pieces 8, 8, the guide piece steering elements I0, I and theguide piece steering elements I3,. I3.

The steering elements I0, I0 have one of their ends Jointedly connected by means of pins 8, 8' with one end of each of the fulcra guide pieces 8, 8 and their other ends with the pins II, II secured in the machine frame. One end of each of the guide piece steering elements I3, I3 is jointedly connected. by means of the pins I2, I2 with the other ends of the fulcra guide pieces 8, 8 and their other ends are pivotally mounted by means of pins I4, I4 in single arm levers I5, I. The pins II, II and I4, I4, forming the fulcra of the guide piece steering elements, are placed on opposite sides of the fulcra guide pieces 8, 8'.

The segment pieces I6, I6 have their vertices pivotally connected, by means of pins I'I, I1, in the centers of the lines connecting the centers of the pins 9, 9' and I2, I2, with the fulcra guide pieces 8, 8. Segment steering elements I8, I8 are jointedly connected, at one of their ends, by means of pins I9, I9, with the segment pieces I6, I6 and, at their other ends, by means of the pins 20, with adjustable blocks 2|, 2| guided in the machine frame, said adjustable blocks being secured in bearings 22, 22 in opposite positions on the machine frame, by means of screws 23, 23 adjustable in the axial direction of the screws and held in position by the nuts 24, 24'. It will be understood that the adjustable blocks 2|, 2| are adapted for adjustment prlor to the operation of the machine and are maintained in a fixed position during the period of operation and that the blocks 2|, 2| can be made adjustable in such a manner that the steering elements I8, I8 be adapted to impart to the rolling down surfaces of the segment pieces either no movement or a more or less powerful movement parallel to the axis of the piece of work in both directions. In the form of embodiment according to the drawings, however, in accordance with the purpose of the invention, only such adjustability is provided that a movement coordinated to the movement of the segment fulcra be imparted to the rolling down surfaces of the segment pieces.

In order to protect the steering guide means against overload, the guide piece steering elements I3, I3 as above described, have one of their ends connected with the single arm levers I5, 15' which are secured by means of their pins 25, 25' rotatably on the machine frame and supported by the piston rods 26,28 of hydraulic pistons 21, 21' which, on exceeding of the permissible maximum pressure, are adapted to yield while displacing the pressure water from the pressure water cylinders 28, 28'.

In order to lift the segment pieces during the return stroke freely over the stretched tube section,'a toggle mechanism coacting with the steering guide means I3, I 3' and the single armed levers I5, I5 is provided. The said mechanism consists of the arms 29, 29, one of the ends of each of which is connected by means of the bolts 38, 30 with the ends of the levers I5, I5, and their other ends, by means of the bolts 3|,3I', with one end each of the cooperation arms 32, 32'. The arms 32, 32 are jointedly secured to the machine frame I by means of the pins 33, 33'. Extensions 34, 34' of the arms 32, 32' cooperate with stationary stops 35, 35' and adjustable set screws 36, 36' of the stationary stops 81, 31'. One the arms 29, 28' pins 38, 38' are secured which are in engagement with the slots 38, 39' of the slotted members 40, 40, the ends of which are pivotally connected with the extensions 42, 42' of the guide pieces 8, 8' by means of pins 4|, 4|.

For holding the piece of work fast during the feed motion and during the stretching, a clamping jaw mechanism is provided which is mounted in the machine frame in front of the rolling segments. It consists, of the guide blocks 43, 43' which are secured to the machine frame parallel to the axis of the piece of work, theslide member 44 which is guided within the guide rails 43, 43', the clamping jaws 45, 46, the clamping jaw actuating mechanism 41, 48, 49, 50, the stationary stop 5| (Fig.2) and the adjustable stop 52. The slide 44 rigidly carries clamping jaws 45 and 46 for engagement with the work and ends underneath the guide rails in extensions 53, 54. The clamping jaw 46 terminates above the guide rails in an arm 55 in the free end of which is secured a bolt 56 on which is rotatably mounted a bell crank lever shank 48 integral with the clamp actuating lever 49. On the free end of the clamp actuating lever 49 is positioned a ball pin 56 engaging with a pull rod 51 which is controlled in some known manner, for instance, by a cam gear secured on the intermediate shaft 4. The shank to move the slide block 44 away from the stop 5| 1 and to press it against the stop or set screw 52 which is adjustably secured in "a stationary bearing 66 and serves to adjustably control the feed stroke.

The stop 5| servesthe purpose of limiting the forward stroke of the clamp as well as to keep the clamp from being carried along with the piece of work while the latter is stretched.

The feed of the piece of work is efiected by a shank 6| (Fig. 2) of a bell crank lever 62 secured by means of a pin 63 in a bearing of the machine frame I and the other shank 64 provided with a roller 65 by means of which the bell crank lever 62 is actuated in the known manner, for instance, by a cam secured on the intermediate shaft '4.

A mandrel bench 66 is secured by means of bolts 61 on the machine frame and carries on its free end a vise 68 comprising jaws 69, III which are constructed as a split bearing in which the mandrel rod 'II is rotatably but axially non-slidably secured through a collar bearing portion I2 provided at one of its ends. As the clamping bolt I3 is provided with oppositely running threads, the bearing halves 69, III can be opened and closed by rotating a hand wheel I4. On the mandrel bench 66, between the vise 68 and the tube feeding mechanism, a device designed for rotating the mandrel rod II is provided, which consists of a bearing I5 and a gear I6 the cylindrical extension H of which is rotatably mounted within the bearing 15. In the hollow space of the extension 11 four pawls IBare pivotally connected to the later and pressed by the compression springs 19 into longitudinal grooves 88 within the mandrel rod II The mode of operation of the above-described rolling-drawing machine is as follows:

For the purpose of setting up the tube to be stretched, drawn or reduced upon the mandrel rod II the machine must first be'brought into a crank circle position which is located between 20 and 110 beyond the forward dead center'position (Figs. 1, 2, 5). In this position thesegment pieces I6, I6 are in the return stroke and are separated from each other and permit a tube to be fed between them. As, in this position, the pull rod 51 presses the ball pin 50 upward, the tensioning jaws 45, 46 are opened. After, by rotating the hand wheel I4, the bearing halves 69, II! have also been opened, the tube a to be drawn can be pushed up on the mandrel rod II from behind in such a manner that the forward end of the tube will be located between or beyond the segment pieces. After the closing of the bearing halves 69, III the machine is started up.

After the cranks, in the continuation of the return stroke, have passed 110 of the crank circle, the tube feeding mechanism 41, 48, 49, 50 is brought into the clamping position by means of the pull rod 51, whereby the closing of the tensioning jaws 45, 46 will be effected. After a further 30 of the crank circle movement the bell crank lever 62 will be forced to turn to the left by the cam drive provided. In so doing the end of the shank 6| impacts on the extension 54 of the slide block 44, pushing the latter together withthe clamping jaws '45, 46 and the tube a forward until the continuation 53 of the glide piece impacts on the stop 5|. In the last .portion of the return stroke the outer ends of the slotted members 40, 48' abut against the pins 38, 38 on the arms 29, 29 and break the previously extended or locked toggle lever 29, 32, 29, 32 the consequence of which will be that the segment pieces I6, I6 which have been lifted off the piece of work during the return stroke will new again be brought into engagement with the same (Fig. 3). As may be seen in Fig. 5, the clamping jaws 45, 46 remain closed until the cranks 2, 2 have reached the forward dead center position, while the slide block 44, remains in its position farthest to the left until the cranks have rotated to about 20 beyond the forward dead center position.

In the rearward dead center position the segment pieces I6, I6 are in their initial position which they occupied prior to the start of the drawing operation (Fig. 3) and which, starting at the rearward dead center position, ends at 34 before reaching the forward dead center position (Fig. 5). In the last '34 before the forward dead center position the members 40, 48 abut. against the pins 38, 38 of the toggle lever shanks 29, 29

and have as their purpose the straightening of the toggle lever mechanism 29, 32 and 29, 32'. Due to this straightening the segment pieces I6, I6 will be lifted off the piece of work' (Fig. 4).

On the infallibly occurring overloading that takes place in the straightened position of the segment pieces I6, I6 and of the steering guide elements 8, I8, I3 and 8', I8, I3 the pistons 21, 21' of the safety cylinders 28, 28 yield and thus make possible also a yielding of the segment pieces I6, I6. As soon as the cranks have exceeded the forward dead center position, the clamping jaws 45', 46 begin to open up. At about 20 after the passing of the forward dead center position the cam transmission releases the roller 65 of the toggle lever 62. Now the compression spring 59 will take eifectwhich moves the slide block 44 to the right so far that it abuts against the adjustable stop 52. As the clamping jaws 45, 46 are open, they can slide back over the tube a without taking it along.

In the crank circle section between 20 and 110 past the forward deadcenter position, the rotation of the mandrel rod H with the tube, to the extent of 90", will be executed. v

Inasmuch as driving and control means 101 the actuation of mechanisms for the turning of the mandrel rod H are known, description of such means has been omitted in order to simplify the graphical illustration and the description of the invention. This can be effected, for instance, by means of a four-part maltose cross which is driven in a suitable manner by the intermediate shaft 4 and drives the gear 16 over a gear transmission,

After the turning of the-tube by 90 a new cycle of the above described operations begin.

It may be noted that the reducing segments l6, l6 are hollowed out or grooved at their working portions sufliciently so that each segment extends about half-way around the tube or the metal stock to be worked. These working portions of the segments are more or less semicircular in cross-section and preferably taper from the rear 8|, 8| to the front 82, 82 (Fig. 2) in the direction of the working stroke. Thus at the beginning of the working stroke an enlarged opening engages the tube and as the stroke progresses, this area or opening decreases until the final exact reduced dimensions are reached. Upper portions of the semi-circular cross-sections are preferably slightly out out or ovalized to prevent the formation of fins along the line where segments meet each other.

The increment of feed of the tube or other metal stock to be Worked may vary depending upon a number of factors, for example, the crosssectional area of the metal stock and the size of the reducing elements. Usually the increment of feed is much smaller than the effective working stroke of the segments so that the segments move over a previously reduced portion of the work piece a number of times. Between each forward or reducing stroke the work-piece is turned or rotated 90 whereby the forward end of the reducing element on the next stroke passes over the previously reduced portion of the metal stock. Ultimately, the work piece, after being acted upon by the reducing elements, two or more times, moves beyond the reducing elements as a finished tube. a

The mandrel used may be cylindricaL'thereby avoiding defects in the inner diameters of tubes attributable to the use of a mandrel section gradually tapering in size in the direction of reducing.

The apparatus may be used either to eifect a substantial reduction in wall thickness of the tube, or to reduce the diameter, or both. The mandrel may be omitted in reducing the diameter of solid or hollow pieces, or in the case of the latter varied in size as will be apparent to one skilled in the art.

Whereas the movement obtained by oscillating a swaging element or segment around a fixed fulcrum as heretofore practiced is a pure rolling movement, the action of the reducing element in the present invention is not only rolling but also sliding or drawing in a line substantially parallel to the work piece. Thus, coaction of diagonal and parallel forces of deformation is obtained. The tubes produced by the pure rolling movement have an inadequate quality of surface. According to this invention a smooth round tube is produced which requires no further finishing.

The deformation forces and power requirements are materially lessened by this invention, as compared to pure rolling methods, on account of the component of force parallel to the axis of the work piece. This decreases the cost of manufacture.

In certain previously proposed reducing machines of the swaging type, the rotating of the tube is effected during the brief interval that elapses after the completion of the forward stroke and before the beginning of the return stroke and the feed of the tube takes place after the completion of the return stroke and before the beginning of the forward stroke. Consequently, when operating at a speed of say 100 strokes per minute, only a short time is available for both operations and the drive means which rotate and feed the tube must operate in the manner of blows. This causes rapid wear and consequent necessity for frequent renewal of the driving means together with loss' of time through interruptions.

In the present machine, considerable sections of the crank circle are available for rotating and feeding the tube, thus making possible normal operation and avoiding shock-like stresses. This is made possible by lifting off the reducing segments from the work piece on the return stroke. The lifting of the reducing segments on the return stroke also avoids distortion of the tube which occurs in the so-called smoothing action of certain reviously proposed reducing machines in which he segment reduces on the forward stroke and comes back in contact with the tube on the return stroke.

The present method also enables a much higher speed of operation than is possible with previously Proposed machines of the type above described which are provided with a carrier for the segments making it necessary to move large masses of weight back and forth in rapid succession and causing early wear on bearings and guide members. By the use of levers and steering means as herein described the masses of weight moved back and forth are substantially reduced.

This invention is additionally characterized by the fact that a simple adjustment of the screws 23, 23' makes it possible to control the motion of the segments I6, IS in order to vary the amount of straight-line or rotary motion, and, if desired, to produce a substantially straight-line (drawing) motion or a substantially rotary (rolling) motion. This is advantageous because it permits adjustment of the machine according to the type of metal reduced or the type of reduction desired. Different types of metals behave differently. With some metals best results in reducing the stock are obtained by deformation forces which are principally diagonal to the axis of the work (rolling forces)" while with others the forces parallel to the axis of the work (drawing) are most desirable. Furthermore, it will be appreciated that by adjusting the position of the set screws 36, 36' the length of the stroke of the reducing or working segments may be varied and controlled as desired.

It will be understood that the invention is applicable to many types of metal including ferrous and non-ferrous metals, e. g., iron, steel, aluminum, brass, and alloy metals. Lubricants may be used in the process in a well known manner. Likewise rust-proofing coatings may be applied prior to reduction.

I Having thus described the invention, what I claim is:

1. A method for the sectional reduction of the cross section of metal stock which comprises intermittently subjecting increments of the metal stock to a combined rolling and drawing action.

2. A method for the sectional reduction of the cross section of metal stock which comprises acting upon the metal stock with reducing elements Which are adapted to move forward over an increment of the metal stock with a rolling movement, while at the same time moving the working surfaces of said reducing elements in a straight line parallel to the direction of the axis of the metal stock.

3. A method for the sectional reduction of the cross section of metal stock which comprises acting upon the metal stock with reducing elements which are adapted to move forward over an increment of the metal stock with a rolling movement, while at the same time moving the working surfaces of said reducing elements in a straight line parallel to the direction of the axis of the metal stock, lifting the reducing elementv after the forward reducing stroke, returning it to its original position out of contact with the metal stock, turning the metal stock through an angle of approximately 90 while the reducing element is out of contact, feeding the metal stock forward in the direction of the reducing stroke a distance such that the portion thereof reduced on the previous stroke is acted upon again by a part of the reducing element on the next stroke, and repeating said operations until the metal stock has been reduced.

4. An apparatus for reducing metal stock, comprising reducing elements adapted to oscillate in contact with the metal stock, fulcra about which said reducing elements oscillate, and means for displacing the said fulcra and the working portions of the reducing elements in a straight line parallel to the direction of the axis of the metal stock to be reduced while simultaneously causing a said elements to swing around said fulcrum.

5. An apparatus for reducing metal stock, comprising reducing elements adapted to oscillate in contact with said metal stock, fulcra about which said reducing elements oscillate, means for imparting a combined rolling and drawing action to said reducing elements and means for changing the ratio between the rolling and drawing components of the action of the reducing elements.

6. An apparatus for reducing metal stock which comprises grooved symmetrically arranged reducing segments adapted to move in contact with said metal stock on the reducing stroke, fulcra around which said segments swing to impart diagonal deforming forces to the metal stock on the reducing stroke, and steering guide elements adapted to impart a straight line reciprocating movement to said fulcra, at the same time that said reducing elements swing around said fulcra, and steering elements adapted to impart a.

straight line reciprocating movement to the reducing segments, whereby the working surfaces of the reducing segments are displaced in a straight line extending parallel to the longitudinal axis of the metal stock being reduced.

7. -An apparatus for reducing metal stock, comprising reducing elements adapted to oscillate in contact with the metal stock around fulcra, steering guide means for simultaneously displacing said fulcra and the working surfaces of said reducing elements in a direction parallel to the axis of the metal stock, means for lifting the reducing.

elements from the metal stock, and means for protecting the reducing elements and the steering guide means against overloading.

8. An apparatus for reducing tubular metal stock, comprising symmetrically arranged grooved segment pieces mounted on fulcra, means for imparting a straight line reciprocating movement to said fulcra comprising steering straight guide elements, means for displacing the segment pieces in a direction parallel to the axis of the metal stock comprising steering elements which have one of their respective ends jointedly secured to the segment pieces and their other ends to members adjustably secured in the machine frame, means for lifting the segment pieces from the metal stock during. the return stroke comprising toggle levers, hydraulically acting pistons moving in safety cylinders and adapted to permit yielding of the mechanism actuating segment pieces and prevent overloading, reciprocating clamping jaws adapted to hold the metal stock during the forward stroke and to feed the stock forward when the segment pieces are lifted from the stock on the return stroke, means for opening and closing said jaws, a cylindrical mandrel ro,d within the tubular stock, and means for rotating the mandrel rod with the tubular stock and elements to swing around said fulcra and to impart diagonal forces to themetal stock, means for. displacing said segments in the direction ofreduction and parallel to the axis of the metal stock whereby a drawing action is imparted to the metal stock at the same time-that a rolling action is imparted to said stock due to the reducing elements swinging around the fulcra, means for lifting the reducing elements from the metal stock and while lifted therefrom returning them to their initial position prior to reduction, and

means for repeating the aforesaid series of operations continuously.

,, ALFRED ImBERGELD. 

